Can I charge a power box

[Ed Brown]

Hi can I charge a power box (booster box) with a 40watt panel and 7a controller


Ed

[inetdog]

Hi can I charge a power box (booster box) with a 40watt panel and 7a controller


Ed

If the booster box has lead acid batteries, yes. Just very slowly.....
If the booster box has Lithium batteries, then the 7A controller may well not have an appropriate voltage setting.

[Ed Brown]

If the booster box has lead acid batteries, yes. Just very slowly.....
If the booster box has Lithium batteries, then the 7A controller may well not have an appropriate voltage setting.

How do I go about it do I wire derlictly from the 7a controller or do I need to go through a inverter. I'm very new to this. I haven't bought anything yet. I want to run 2 fans from the power box and have solar charging as the fans are running during sunny hot days. Is that possible with this set up

Ed

[jony101]

just connect directly from the controller to the battery, 40 watt panel only puts out 2 amps at max sun light. 2 amps wont hurt your booster pack. When I plug into the wall I use a 2 amp charger on my booster pack and you can charge some booster packs from your car cigarette lighter which can put out up to 15 amps. the booster pack will only take the amps it needs. The only thing that will harm the battery is high voltage, as long as you stay under 14.4 volts you will be ok. High voltage will force the battery to take more amps than it needs and it will boil the electrolyte.

I use to charge my 17 ah agm battery booster pack with my 120 watt panel without any problems, i've also connected my 240 watt panel and its 20 amp mppt controller to the same pack also without any issues.

Running fans from the booster pack while charging it should be no problem, unless the fans use more power than your 40 watt panel can put out, then your battery will never charge. If you know how much amps your fans use get the appropriate size panel for it, about 20 watts for every amp.
you can leave the panel connected directly to the battery all the time, once battery is full it will be floating at less than an amp and you only see the amps go up when you turn on the fans.

An example a 12 volt fantastic fan uses 3.5 amps and would need about 80 watts of panel.

[PNjunction]

just connect directly from the controller to the battery,

If the pack does not have a dedicated dc jack, then you can do so from the clamps. Be careful, as the clamps are live. Attach controller to battery first, and the panel connection to the controller last - if you do it backwards, the controller may think you have a really dead battery (it doesn't know that it is missing entirely temporarily!) and may try to protect this phantom battery with either no output, or some might default back to a float-only setting from the outset.

When I plug into the wall I use a 2 amp charger on my booster pack and you can charge some booster packs from your car cigarette lighter which can put out up to 15 amps.

Yes, but doing the direct connect to the vehicles battery with up to 15a unregulated (10a fused more commonly) is NOT recommended for regular use and is to be used as a last ditch effort. The reason, despite what powerstream says, is that the typical ups-style agm inside these packs are best run no higher than 0.3C continuous for both charge and discharge. Despite the speed, these batteries are not the highest quality in the first place. Their paste / build quality are not designed for high-amperage. You'll see that they are built cheaply, and use general-purpose agm's.

In other words, don't do this often as cycle life will suffer. Consider that the jump packs are designed for very INFREQUENT jump use, not regular SLI / fast-charge duty and that is why they can get away with a cheap gp agm inside where the consumer will usually outlive the cycle rating of the pack, and not see the hot-spots that develop within the material when they follow the "fast charge is ok" conspiracy theorists.

i've also connected my 240 watt panel and its 20 amp mppt controller to the same pack also without any issues.

Well, none that you can detect. You may want pull your internal general-purpose agm out, and inspect it with an IR thermometer under charge from say at least a 50% DOD. If nothing physically is noted, then what you don't see is the reduced cycle life. Sure it "works", but in the long run if you do this regularly, you'll just be buying a new battery sooner.

Always consider the entire life-cycle cost when going outside the bounds of what the engineering department recommends. If you know what you are doing, great. If the battery distributor and the manufacturer disagree, ask yourself who is going to eat your warrantee? Will it be the distributor or you? Will they provide free replacements with your fast-charge regimen when it doesn't live up to the cycle-count claims?

Also note that the op is talking about a 7ah internal battery, whereas you are using a 17ah version.

Tip: if you want to do the fast-charge routine regularly, then use a battery designed for it! Look into the small pure-lead's from Odyssey. Here, where it costs more initially, you'll be rewarded with much higher cycle life.

[inetdog]

Many of the jump/boost packs explicitly recognize that neither the internal battery nor the clamps and jumper wires are capable of starting a large engine on their own. The instructions tell you to leave the pack connected for a period of time (~15 minutes) during which time the pack is recharging the vehicle battery far enough to let it provide the majority of the starting current. That recharging function can even be used through the cigarette lighter adapter cord.
The pack might be capable of starting a warm engine on a subcompact on its own, but not a full size V-8.

The power packs that tow companies carry are an entirely different order of capability!